Millimeter-wave wideband bandpass filter using novel slotted substrate integrated waveguide

In this paper, a millimeter-wave wideband bandpass filter is proposed and designed by using novel slotted substrate integrated waveguide (SIW) units. The unit consists of two pairs of same size dumbbell slots etched on both the top and bottom metal planes of the SIW. The slots act as shunt resonators, which reduce the filter size and produce transmission zeros simultaneously. A five-order bandpass with a center frequency of 32.5 GHz and a 3dB fractional bandwidth of 34.6% is developed, and it is small in size, and low loss with a measured insertion loss of 1.54 dB at the center frequency.